SURFACE IMPEDANCE NEAR CYCLOTRON EDGE FOR HELICONS IN POTASSIUM

An extension of the theory of the anomalous skin effect given by Reuter and Sondheimer to include a magnetic field is used to calculate the surface impedance of a semi-infinite free-electron metal. The magnetic field and the helicon propagation are directed perpendicular to the metal surface. Parameters appropriate to potassium are used in the numerical calculations. Near the cyclotron absorption (Kjeldaas) edge the assumptions of perfectly specular (p=1) and completely diffuse (p=0) reflection of the electrons at the metal surface lead to significantly different results for the surface impedance. The theory is compared with Taylor's experimental work on potassium. The data for the surface reactance agree well with the theory for p=0, the data for the surface resistance do not show satisfactory agreement with the theory for p=0 or p=1. Possible explanations for this incomplete agreement are presented. © 1968 The American Physical Society.